“If the people’s hopes are not to be dashed, the incoming president and his government should quickly turn his promises into concrete action and take steps to improve human rights,” he added.

Buhari’s tenure as a military head of state was marked by arbitrary arrests, restrictions on freedom of expression and the media.

However, during the election campaign, he acknowledged these past problems and promised that there would be a change.

According to Human Rights Watch, since Nigeria returned to civil rule in 1999, more than 20,000 civilians have been killed in sectarian, communal, or political violence and almost 1.5 million people have been displaced from their homes.

Very few of those responsible for the violence, whether state or non-state actors, have been arrested or prosecuted.

In combating Boko Haram, Nigerian security forces have been implicated in grave violations of human rights and international humanitarian law, including incommunicado detention of Boko Haram suspects without charge or trial, and extrajudicial killings.

While some soldiers have been prosecuted in military tribunals for offences such as cowardice and mutiny, almost no one in the security forces has been held for human rights abuse, says Human Rights Watch.

“Buhari needs to end the cycle of violence and take bold action to ensure the judiciary investigates and prosecutes anyone implicated in serious human rights abuses, whether Boko Haram fighters or the military and police,” Segun said.

The incoming government should end divisive state and local council policies that discriminate against non-indigenes and sponsor legislation to bar all federal, state, and local council institutions from unlawful discrimination against this class of people.

The rights group also urged the new administration to take immediate steps to strengthen watchdog institutions such as the Code of Conduct Bureau, the Economic and Financial Crimes Commission (EFCC), and the Independent Corrupt Practices Commission (ICPC) to allow them function without interference or partiality.

Human Rights Watch further asked the new administration to also repeal the Same-Sex Marriage (Prohibition) Bill, which President Goodluck Jonathan ratified in January 2014.

The group said the law contradicts Nigeria’s constitution and international human rights treaties, criminalizes public display of affection between same-sex couples and penalizes organisations advocating the rights of LGBT people.